ON THE FAUX A OF JAPAN. 107 



tion of animals in certain regions is influenced not only by physical 

 but also by historic factors. In order to point out the nature and 

 quantum of the peculiarities in the fauna of Japan, we would pass 

 on to the consideration of the fauna, first dividing it into two fields, 

 land and marine. 



It is a pleasure to acknowledge the aid received in the matter of 

 distributional data from the following zoologists — Professor K. Kishi- 

 nouye. in many respects ; Professor S. Watase, some general aspects ; 

 Professor J. Hara, oceanic currents ; Dr. S. Tanaka, fishes ; Mr. K. Tago, 

 whales and salamanders; Mr. K. Kishida, mammals; Mr. Y. Okada, 

 frogs ; and Mr. Y. Y^^koya, crustaceans. 



Land Fauna. 



As previously pointed out, Japan possesses an exceedingly rich and 

 varied fauna closely related to the adjacent continent, and presents us 

 with two pricipal groups, one Palaearctic, the other Oriental. Of these 

 the Palaearctic elements are chiefly found in the northern territories, 

 such as the Kuriles, Saghalien, Hokkaido, Japan proper, and Korea, 

 while the Oriental ones range over the islands of Formosa and I.oo- 

 choo. With regard to the boundary line between these two regions 

 there is a difference of opinion. JMaking use of some data on the 

 distribution of certain insects, Miyake and Esaki are inclined to locate 

 it between Kyushu and Tauegashima. On the other h.and, some 

 authorities (Watase, Aoki, Kuroda, Okada, Kishida, and others), 

 approaching the question from the consideration of vertebrates and 

 others, adduce arguments of considerable weight in favour of the view 

 that the pass between Yakushima and Amami-Oshima must be con- 

 sidered as forming a distinct boundary. At present, the latter view is 

 generally accepted. 



As is the case with the Eurasian continent, two more or less 

 distinctly marked subregions can be distinguished in the island grouj) 

 of a Palaearctic character, the northern subregion generally known as 

 the Em-asian (Siberian), and the southern, or Eastasian (Manchurian) . 

 From a consideration of the distribution of some birds and mammals, 

 Blakiston puts forth the view that Hokkaido and the more northern 

 islands are, ^oologically speaking, portions of the Eurasian subregion, 

 from which Japan proper is cut off by a decided line of demarcation 

 in the Tsugaru strait. This boundarv we call Blakiston's line. 



